摘要:

The temperature rise in an ion‐implanted silicon sample illuminated by a pulsed laser (ruby or Nd : YAG) is determined by numerical solution of the heat‐diffusion equation. The temperature dependence of the thermal conductivity and the free‐carrier absorption are included in the calculations. The latter was found to have a very significant effect when the laser is operated in theQ‐switched mode. The analysis shows that annealing in this mode almost certainly involves melting of the sample surface. In the free‐oscillation mode, however, free‐carrier absorption is negligible, and this mode may therefore provide a method of melt‐free annealing.

ISSN:0003-6951    

DOI:10.1063/1.90777

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Multiple‐quantum‐well Ga1−xAlxAs‐GaAs heterostructures grown by metalorganic chemical vapor deposition have been analyzed by Auger electron spectroscopy combined with simultaneous argon‐ion sputter etching. The chemical‐interface widths of the Ga0.45Al0.55As‐GaAs heterojunctions are determined to be ≲17 A˚. In addition, no Al is detected in the GaAs quantum wells.

ISSN:0003-6951    

DOI:10.1063/1.90778

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Preferential diffusion of various gases down the grain boundaries in polycrystalline silicon is shown to promote significant changes in the density of defect states in these regions. A plasma of monatomic hydrogen provides a significant reduction in both the state density and the accompanying grain‐boundary potential barrier while plasmas of oxygen, nitrogen, and sulfur hexafluoride are shown to increase this density of states. Boundaries passivated with hydrogen have as much as a factor of 1000 larger transconductance after treatment. Hydrogenated barriers are stable over long periods at 375 °C and essentially indefinitely at 23 °C. The results have important implications for the development of low‐cost thin‐film silicon photovoltaic devices.

ISSN:0003-6951    

DOI:10.1063/1.90779

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Quantum effects are being studied in the transverse magnetoresistance of degenerate semiconductors such as highly dopedn‐type InSb for the case where acoustic phonons are the dominant scattering mechanism. The result shows that the transverse magnetoresistance oscillates with the dc magnetic field owing to the degeneracy of the electron gas. However, the transverse magnetoresistance for nonparabolic bands is enhanced due to the strong magnetic field dependence.

ISSN:0003-6951    

DOI:10.1063/1.90780

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The sputtering yields of Ag, Au, and Pt have been measured for monatomic and polyatomic ions of P, As, Sb, and Bi over the energy range 15–135 keV. Very lare enhancements of the sputtering yields over those predicted by linear cascade theory have been observed. These enhancements appear to be consistent with a strong contribution resulting from the near‐surface region of the impact area and that the complete collision cascade, even for high energy densities, plays a lesser and possibly minor role. It is also shown that the enhancements can in no way be explained based upon a thermal model in which the localized high‐temperature zone is responsible for an evaporation component.

ISSN:0003-6951    

DOI:10.1063/1.90781

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The rapid onset of quasiparitcle tunneling current in superconductor‐insulator‐superconductor (Josephson) junctions at voltages above 2&Dgr;/eis being used for millimeter‐wave heterodyne mixing. Junctions with a 2‐&mgr;m diameter andRN=50 &OHgr; have little capacitive shunting at the signal frequency of 36 GHz. Because there is no series resistance, residual capacitance can be tuned out. Double sideband conversion efficiencies of 0.32 and mixer noise temperatures as low asTM⩽7 K=4h&ngr;/khave been observed. The results are compared with shot‐noise‐limited mixer theory. Photon‐assisted tunneling effects are seen which indicate the approach to photon‐noise‐limited operation.

ISSN:0003-6951    

DOI:10.1063/1.90782

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Small‐area (≲1 &mgr;m2) oxide‐barrier tunnel junctions have been made of thermally cyclable superconducting Pb alloys for use as high‐frequency mixers. A single‐sideband mixer noise temperature of <100 K has been achieved at 115 GHz. This result was achieved in the quasiparticle (classical) mixing mode.

ISSN:0003-6951    

DOI:10.1063/1.90783

出版商:AIP    

年代:1979

数据来源: AIP